Materials Data on ErCuS2 by Materials Project
ErCuS2 crystallizes in the orthorhombic Pnma space group. The structure is three-dimensional. Er3+ is bonded to six S2- atoms to form ErS6 octahedra that share corners with four equivalent ErS6 octahedra, corners with six equivalent CuS4 tetrahedra, edges with four equivalent ErS6 octahedra, and edges with three equivalent CuS4 tetrahedra. The corner-sharing octahedral tilt angles are 51°. There are a spread of Er–S bond distances ranging from 2.64–2.79 Å. Cu1+ is bonded to four S2- atoms to form CuS4 tetrahedra that share corners with six equivalent ErS6 octahedra, corners with two equivalent CuS4 tetrahedra, edges with three equivalent ErS6 octahedra, and edges with two equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 14–59°. There are a spread of Cu–S bond distances ranging from 2.30–2.41 Å. There are two inequivalent S2- sites. In the first S2- site, S2- is bonded in a distorted rectangular see-saw-like geometry to three equivalent Er3+ and one Cu1+ atom. In the second S2- site, S2- is bonded to three equivalent Er3+ and three equivalent Cu1+ atoms to form distorted edge-sharing SEr3Cu3 octahedra.